Carbamazepine treatment of bipolar disorder: a retrospective evaluation of naturalistic long-term outcomes

Background: Carbamazepine (CBZ) has been used in the treatment of bipolar disorder, both in acute mania and maintenance therapy, since the early 1970s. Here, we report a follow-up study of CBZ-treated bipolar patients in the Taipei City Psychiatric Centre. Methods: Bipolar patients diagnosed according to the DSM-IV system and treated with CBZ at the Taipei City Psychiatric Centre had their charts reviewed to evaluate the efficacy and side effects of this medication during an average follow-up period of 10 years. Results: A total of 129 bipolar patients (45 males, mean age: 45.7 +/- 10.9 year) were included in the analysis of CBZ efficacy used alone (n = 63) or as an add-on after lithium (n = 50) or valproic acid (n = 11), or the both of them (n = 5). The mean age of disease onset was 24.6 +/- 9.5 years. The mean duration of CBZ use was 10.4 +/- 5.2 year. The mean dose used was 571.3 +/- 212.6 mg/day with a mean plasma level of 7.8 +/- 5.9 mu g/mL. Mean body weight increased from 62.0 +/- 13.4 kg to 66.7 +/- 13.1 kg during treatment. The frequencies of admission per year before and after CBZ treatment were 0.33 +/- 0.46 and 0.14 +/- 0.30, respectively. The most common side effects targeted the central nervous system (24%), including dizziness, ataxia and cognitive impairment. Other common side effects were gastrointestinal disturbances (3.6%), tremor (3.6%), skin rash (2.9%), and blurred vision (2.9%). Eighty-eight patients (68.2%) were taking antipsychotics concomitantly. Ninety-six patients (74.4%) needed to use benzodiazepines concomitantly. Sixty-three (48.8%) patients had zero episodes in a 10-year follow-up period, compared to all patients having episodes prior to treatment. Using variable analysis, we found better response to CBZ in males than in females. Conclusions: CBZ is efficacious in the maintenance treatment of bipolar disorder in naturalistic clinical practice, either as monotherapy or in combination with other medications. CBZ is well tolerated by most patients in this patient group.